0

An API in my spring boot app has a query parameter of an Enum type. From the postman, it accepts only Enum string value. It responds with 400 for integer when sent as the query parameter value. How to configure for spring boot app to accept Enum string values or Enum index/ordinal values as query parameters.

below both the ways should work

  1. <base-url>/123/status?status=inprogress
  2. <base-url>/123/status?status=2 (2 is index of inprogress enum)

I am using Java, spring boot fw. It works well in dotNet

Renis1235
  • 4,116
  • 3
  • 15
  • 27
Te Jas
  • 45
  • 9

1 Answers1

1

As far as I know, there is no way to do this magically with an annotation or so. What you could do is implement a custom converter and convert the value inputted into your enum like this:

public class MyCustomEnumConverter implements Converter<String, YourEnum>
{
    @Override
    public YourEnum convert(String source) {
        try
        {
            if(isNumeric(source)) // If the string passed is a Number
            {
                int index = Integer.parseInt(source); 
                return YourEnum.values()[index]; // Get the Enum at the specific index
            }
            // Else if it is a string..
            return YourEnum.valueOf(source);
        } catch(Exception e) {
            return null; // or whatever you need
        }
    }

    private static boolean isNumeric(String str) {
        try {
            Integer.parseInt(str);
            return true;
        } catch(NumberFormatException e){
            return false;
        }
    }
}

And then register your Converter:

@Configuration
public class MyConfig extends WebMvcConfigurationSupport {
   @Override
   public FormattingConversionService mvcConversionService() {
       FormattingConversionService f = super.mvcConversionService();
       f.addConverter(new MyCustomEnumConverter());
       return f;
   }
}

You could improve the logic of MyCustomEnumConverter but for the sake of simplicity, I left it at that.

If you want to apply the specific Converter to just one controller check this answer.

Renis1235
  • 4,116
  • 3
  • 15
  • 27
  • Thank you for the quick reference. Will this setup auto-convert my int query param value to actual enum when it reaches the controller or Do I need to use any ConversionService to get this converted manually? – Te Jas Oct 12 '21 at 13:32
  • It should do this automatically. Just use the `@RequestParam` annotation and your `enum` type. – Renis1235 Oct 12 '21 at 13:34
  • I have enabled this. It starts working but it is impacting few other places internally. I am seeing this issue at some other implementation while fetching data from repo - "Unable to evaluate the expression Method threw 'org.hibernate.LazyInitializationException' exception." Not able to figure out how this is related to the change I made. If I disable my Configuration class for Converter, I am not seeing the exception ! @Renis1235 – Te Jas Oct 12 '21 at 17:35
  • 1
    Check this out then https://stackoverflow.com/questions/57536693/how-to-use-spring-converter-for-some-controllers-only . Use the Converter only on your one controller. The two error messages have nothing to do with each other though. Try it and reply if it works. – Renis1235 Oct 12 '21 at 17:51
  • Worked! Thanks a ton @Renis1235 :) – Te Jas Oct 12 '21 at 19:04